Summary: Our identity as Christians comes from who our Father is.
Have you ever noticed how many Hispanic last names end in -ez? Have you ever wondered why that is? In Old Spanish, -ez meant "son of." Therefore Gonzalo’s son would be called Gonzalez, Domingo’s son would be called Dominguez, etc. And almost every language has the same thing. For the Armenians, it’s the names that end in -ian. The Poles use -ski. For the Irish, it’s the names that begin in O-; the Scots use Mc-. It’s easier to see in modern day English, with Johnson, Williamson and Robertson. The point is that for centuries men have identified a man by who his father was.
John 1:12 tells us that Jesus came to give us the right to become children of God. We can now be called sons of God.
1) We are sons of God if we are led by the Spirit.
a) As opposed to the flesh (“sinful nature”). So many things that are seen as "natural" are things that go against God.
b) Minds set on what the Spirit desires. (vs. 5) Can you say that your mind is set on what God wants? Are your daily decisions guided by what God’s will is, by what is best for the Kingdom of God, by what fits best with what his Holy Word says?
c) 1 Peter 1:14-17 tells us that calling God father obligates us to live holy lives.
Illustration: Do you remember the movie "The Lion King"? It tells the story of a young lion who is the son of the king. The lion runs away when his father is accidentally killed and the cub is made to feel responsible for that death. He takes refuge with a pair of insectivores, and we see the king of the beasts reduced to a life of eating bugs. Then at one point his dead father appears to him (if any are concerned by this, remember that this is a movie about animals that talk!) and says to him, "Remember who you are." He had forgotten who he was. He wasn’t a bug eater. He was the son of the king.
God says the same thing to us: "Remember who you are." We are to live as sons of the king.
2) We are not slaves to fear, but sons.
a) Life and peace (vs. 6). Following the path of the world leads to strife and death. It doesn’t take much investigation to see that principle at work in our world. Following the leading of the Spirit leads to life and peace.
b) Submitted to God’s law. Even as sons of the king, we are responsible for following the king’s commands.
3) Heirs with Christ -- what a glorious image. Even though we are adopted sons, we have become co-heirs with the one and only Son.
a) Share his sufferings -- This is a part of the gospel that we often miss. Jesus said that in this world we would have tribulation (John 16:33). Paul and Barnabas taught their converts in Acts 14 that they would have to suffer to enter the Kingdom (Acts 14:22). Paul said that he wanted to share in the suffering of Christ in order to share in his resurrections (Philippians 3:10-11).
b) Share his glory -- Look at Romans 8:18. Even if we suffer in this life, can we compare that suffering to an eternity of glory? What if we laid out all of eternity in a long line which had no end... how much of that line would represent our life on earth? Even a speck would be too big. It is not too much to suffer in this life to gain an endless life of glory.